Grinding-plate fob



a. WOLFF.

GRINDING PLATE FOR ATTRITION MILLS.

APPLICATION FILED NOV.29, 1920.

Patented Dec. 13, 1921.

2 SHEETS-SHEET I.

3 5 .wmmwwww WITNESS.

LLS.

. APPLICA'HON FILED N0V.291'1920- Patented Dec. 13, 1921.

2 SHEETS-SHEET 2.

GEORGE WOLFE, OF PATERSON, NEW JERSEY.

GRINDING-PLATE FOR ATTRITION-MILLS.

Specification of Letters Patent.

Patented Dec. 13, 1921.

, Application filed November 29, 1920. Serial No. 427,000.

To all whom it may concern Be it-known that I, GEORGE-WOLFE, a citizen of the United States, residing at Paterson, in the county of Passaic and State of New Jersey, have invented certain new and useful Improvements in Grinding-Plates for AttritiornMills, of which the following is a specification.

This invention relates to the grinding plates of attrition mills and the like. The object of the invention is to improve these plates in respect to their cutting action and the freedom of flow between them of the material being treated. The cutters in my improved plate are so arranged that they act not only as cutters but at their ends in a novel and improved way as a succession of stops to the flow of the material. Where stops are used in such plates as heretofore proposed they have been in the nature of a cross-wall traversing the space between each two adjoining cutters, so that as the material which lodged at these points could not escape it would jam and frequently the thusaffected portions of the working face of the plate would be torn away; orthey have been afforded by the ends of the blades or cutters, but only in such a way as to allow too much freedom of flow. Many advantages flow from the present invention, as will be apparent to those skilled in the art, among which may be named the more even distribution with respect to all parts of the working face of the cutting action and of the wear of the cutters; an increase in the amount of actual working or cutting surface to a given area; the flow of the material without danger of congestion but with not too great freedom; the possibility of operating at slower speed in the turning out of a given quantity of product; avoidance of damage to the working face of the plate; re-

duction of friction and consequent heat, etc.

One form of my invention is fully illustrated in the accompanying drawings, in which Figure 1 shows my grinding plate in plan, only one sector of which appears in full lines, the rest appearing in dotted outline;

Fig. 2 shows on a larger scale fragments of two cooperating plates constructed according to my invention, the cutters of the near plate being shown dotted and their dotted outline being further extended at the left beyond the part of said near plate actually appearing so as to illustrate their working relation to the cutters of the other plate; and Figs. 3, 4, 5 and 6 are sectional views on llnes 33, 4-4, 5-5 and 66 of Fig. 2.

It Wlll be understood that in an attrition m ll embodying my invention the two plates Wlll preferably be reverse counterparts of each other, so that the following detailed description of one will serve for both. I

shall further confine myself to describing the details of but one of the sectors of the plate, as the sectors are all alike.

The plate a, whose sectors are to be bolted to its suitably rotated carrier or head (sockets for the bolt-heads appearing in the drawings at Z2), is as usual a sectional disk having an opening 0 at the center and a general inside bevel d at said opening, thus to permit the grain or other material supplied axially to find its way between the plates.

Each sector of theplate is preferably divided into a series of what are substantially smaller sectors, there being four such smaller sectors shown in Fig. 1. These smaller sectors are separated from each other by partitions e which to the naked eye appear to be radial but which lie in fact, in chords passing close to the center of the plate; these partitions do not follow the bevel (Z but each presents av level edge from the inner to the outer perimeter of the sector (see Fig. 3), and each is preferably thickened up at its inner end portion, (Figs. 1 and 2), to strengthen it at this point.

Each smaller sector or subsector has series of spaced blades or cutters g, the series being arranged in succession from the inner toward the outer perimeter, and all the cutters are arranged parallel to the right-hand partition 6 of such sub-sector. The cutters in each series are preferably all straight and of the same length, and at each end they are trued up to a line that is perpendicular to the right-hand partition 0 of the sub-sector to which said series belongs. The tops of the cutters, which of course all lie in the same plane, are appreciably narrower than the spaces between them; the grinding plate shown is supposed to revolve counter-clockwise, and so the left side or lateral face 9 of each cutter shown in the drawings is a vertical side, forming with the top surface of the cutter its cutting edge, while its opposite side or lateral face 9' slopes to the right till it reaches the vertical side 9 of the next adjoining right-hand cutter in the same series. The tops of the cutters in any series are opposite the spaces between cutters in the adjoining series and the planes of the faces 9 g of a cutter in any one series intersect the planes of the adjoining lateral faces of two adjoining cutters in the next series, so that the cutters are in effect staggered and also overlap in the several series, and since the tops of the cutters are narrower than the spaces between them it follows that the spaces in adjoining series of cutters are put into communication with each other; in the construction actually shown each space in one series is thus put into communication with two spaces in a neighboring series, because the top of the cutter separating the latter two spaces is centrally opposite the former space. The cutters in any series may project somewhat between cutters of adjoiuing series, as shown. 7

I have found that the sectors may be cast or molded, the working face being afterward ground off smooth to produce the cuttin edges on the cutters.

The operation of a grinding plate con structed in accordance with my invention will be readily understood by those skilled in the art. The plate being in rotation and face to face with another grinding plate,

- preferably a reverse counterpart of itself,

and the material to beground being fed to and between the plates at the opening a, it is by centrifugal force impelled toward the periphery of the plates as usual. The cutter edges being all arranged in chords, and so that those of one platecross those of the other at a sharp angle, the cutting action is a distinct shearing one. The retardingof.

the material against the influence of centrif-' ugal force is effected by the inner ends of the cutters, which do not block the escape of the material toward the outer perimeter of the plates so that there would be any permanent lodgment thereof at any point but permit it to work laterally and thereby find egress into a space in the next outer series: any tendency for the material to lodge at the inner end of a cutter is obviously discouraged by the transverse displacement to which itois. subjected on account of the relative movement of the plates transversely of the cutters. Any tendency of the material to jam in the passages (which I have marked 71.) 0f communication between adjoining spaces is discouraged by displacing action of the outer ends of the next inward series of cutters on the opposite plate, it being noted that the lines, as w, inwhichthe ends of the cutters on one plate lie move in shear-like relation to the corresponding lines, as y, in which the ends of the cutters on the other plate lie. Since the top of each cutter is narrower than the space opposed thereby between cutters in the adjoining series and since its lateral faces are in planes intersect-V ing the adjoining faces of the latter cutters it follows that material traveling outwardly along the face 9' of any cutter in response to centrifugal'force has its progress checked by the inner end of a cutter inthe next outer series; also that each cutter is thus made strong and well adapted to withstand the strains imposed on it. s V.

It may be remarked that the partitions e are themselves cutters, the cross sectional shape of each being the same as that of any face portion and said series being arranged at different distances from the center portion of the grinder surface and each series having the blades therein respectively opposite, and narrower at their tops than, the spaces between'the blades in the adjoining series.

2. A grinder surface for a rotary attrition mill having sector-shaped grinder surface portions whose sides are radii from the center of rotation as between such grinder surface and a corresponding opposed grinder surface, each such sector-shaped surface portion being composed of series of spaced straight blades all arranged substantially parallel with one of said sides of said surface portion and said series being arranged at different distances from the center portion of the grinder surface and each series having the ends of the blades therein extending into, and narrower at their tops than, the spaces between the blades in the adjoining serles.

In testimony whereof I affix my signature.

GEORGE WOLFF. 

